University of Kentucky
How Does Insulin-Degrading Enzyme (IDE) Gain Access to its Substrates? A Study of IDE-Phosphatidyl Inositol Phosphate (PIP) Lipid Interactions
Grade Level at Time of Presentation
Senior
Major
Biochemistry
2nd Grade Level at Time of Presentation
Senior
2nd Student Major
Neuroscience
KY House District #
6
KY Senate District #
13
Faculty Advisor/ Mentor
David Rodgers, PhD.
Department
Department of Cellular and Molecular Biochemistry
Abstract
Insulin-degrading enzyme (IDE) is a protein linked to Alzheimer’s Disease and Type II diabetes. This connection was made because IDE breaks down insulin and the amyloid-beta protein, which makes it a potential therapeutic target for these diseases. While IDE is found within the main cytosolic compartment of a cell, insulin and amyloid-beta are usually located within subcellular endosomal compartments. This research aims to determine how IDE gains access to the molecules it digests despite being separated from them by a lipid membrane. It is hypothesized that IDE initially localizes by binding to phosphatidylinositol phosphate (PIP) lipids that are found in the endosomes’ lipid membrane.
Previous research has identified a site on IDE where these PIP lipid head group interactions may be occurring. This research tested the validity of this site using an enzyme-linked immunosorbent assay (ELISA), which was used to quantify the level of interaction between IDE and artificial membranes known as liposomes. Results demonstrated that mutations to the proposed binding site affected IDE-PIP interactions. In particular, the variants IDER824A,H885A,R892A and IDEQ813A,N821A,H885A showed reduced or no detectible levels of liposome binding when compared to normal IDE. These results support the hypothesis that IDE interacts specifically with PIP head groups and that this interaction occurs at the proposed binding site. Improved understanding of this mechanism could someday enable the development of therapeutics for Alzheimer’s disease and/or Type II Diabetes and explain why diabetes patients so often develop Alzheimer’s Disease later in life. Considering over 30,000 Kentuckians are diagnosed with diabetes each year, these findings could have a massive local impact and improve health outcomes for Kentucky and beyond.
How Does Insulin-Degrading Enzyme (IDE) Gain Access to its Substrates? A Study of IDE-Phosphatidyl Inositol Phosphate (PIP) Lipid Interactions
Insulin-degrading enzyme (IDE) is a protein linked to Alzheimer’s Disease and Type II diabetes. This connection was made because IDE breaks down insulin and the amyloid-beta protein, which makes it a potential therapeutic target for these diseases. While IDE is found within the main cytosolic compartment of a cell, insulin and amyloid-beta are usually located within subcellular endosomal compartments. This research aims to determine how IDE gains access to the molecules it digests despite being separated from them by a lipid membrane. It is hypothesized that IDE initially localizes by binding to phosphatidylinositol phosphate (PIP) lipids that are found in the endosomes’ lipid membrane.
Previous research has identified a site on IDE where these PIP lipid head group interactions may be occurring. This research tested the validity of this site using an enzyme-linked immunosorbent assay (ELISA), which was used to quantify the level of interaction between IDE and artificial membranes known as liposomes. Results demonstrated that mutations to the proposed binding site affected IDE-PIP interactions. In particular, the variants IDER824A,H885A,R892A and IDEQ813A,N821A,H885A showed reduced or no detectible levels of liposome binding when compared to normal IDE. These results support the hypothesis that IDE interacts specifically with PIP head groups and that this interaction occurs at the proposed binding site. Improved understanding of this mechanism could someday enable the development of therapeutics for Alzheimer’s disease and/or Type II Diabetes and explain why diabetes patients so often develop Alzheimer’s Disease later in life. Considering over 30,000 Kentuckians are diagnosed with diabetes each year, these findings could have a massive local impact and improve health outcomes for Kentucky and beyond.